Date   

Re: 7000 series white plug-in connector

 

When my cohort gets out of the hospital, he has a 7613 in the basket for sure. The wrong person worked on the power supply and I couldn't get it going again. Storage also quit on it before that.

We also have some plugins, so it is ripe to try and build a set of extenders for it since they don't seem to readily available. That part of the scope will come apart for that.

Problem is he had open heart surgery and has no idea when they're going to cut him loose, or what kind of shape he'll be in. You might end up epoxying it first.

And to comment on that, there is no harm in trying, it is broke anyway. I would also consider using zip ties to clamp it together. I don't believe it broke due to force, it is only an edge connector. The plastic is probably brittle from outgassing for 40 years or whatever.

Keep us posted on if it works, if not I'll see what I can do. At least he lived...


2465B front bezel needed

 

Looking for a front bezel for a 2465B in excellent or better condition. Doesn’t need to have 2565B name badge.

Thanks in advance,

Manuel W4SSB


Re: 475 switch lettering

Fabio Trevisan
 

Hello,

The ganged push button caps of the 475, just as much as the 465 and others of the same vintage are all removable.
They're tight fit and it takes quite a good grabbing from their sides to pull the off.

A nose pliers with the tip covered by rubber will help to obtain a good grip while protecting the buttons from being scratched by the pliers.

Also, if the scope is opened, you can use a lever and push the caps out, from behind the front panel (some buttons may be difficult to reach from behind).

Rgrds,

Fabio

On Fri, Aug 24, 2018 at 01:03 PM, KL7AM wrote:


Lettering is mostly gone on most of the push switches. I have a parts 475 with
good lettering and am curious if I would have to swap the whole switch
assembly or do is there an easier way?


475 switch lettering

KL7AM
 

Lettering is mostly gone on most of the push switches. I have a parts 475 with good lettering and am curious if I would have to swap the whole switch assembly or do is there an easier way?


Re: 464

Fabio Trevisan
 

Hello Jim,
I don't quite understand what you mean... Q1486 is grounded, but not its carcass. The emitter goes to ground (via wire and A6 main interface board PCB's ground).
Maybe you're not looking to the correct schematic?
The +V power supply enters the top end of T1501 transformer's primary winding (pin 5, heavily decoupled by C1487 and C1487). The lower end of the primary winding (pin 6) is connected to the collector of Q1486, whose emitter goes to ground, closing the circuit. The primary of T1501 is the collector load of Q1486, which works as a simple common emitter amplifier.
What you call the second primary winding (pins 3 and 4) is, in fact, a low voltage, feedback secondary winding... It provides positive feedback to the base of Q1486 and it's actually what makes the circuit behaves like an oscillator.
Operating principle is as follows:

1. Assume (for the sake of understanding) Q1484 is not conducting (its conduction is not essential for the oscillation... it just controls how much more intense or less intense circuit will oscillate).
2. Assume Q1486 starts not conducting... there's no current flowing through the primary (and no magnetic field).
3. R1483 (5k6) provides bias to Q1486 through T1501 feedback winding. At this point there's 0V accross this winding, because the primary has no current (yet).
4. As current flows from R1483, through T1501 pins 3 and 4, and enters the base of Q1486, Q1486 starts to conduct... A current starts to flow through T1501's primary.
5. As current flows through T1501 primary, magnetic field starts to build up, and a voltage is induced on the feedback winding of T1501. The feedback winding is wired such a way that this voltage increases the bias to Q1486 (the voltage sums up to what is already coming from R1483)... making Q1486 conducts harder and harder...
6. At some point, Q1486 reaches near saturation, and current through the primary winding stops increasing... (and magnetic field stabilizes).
7. As magnetic field stabilizes, the induction to the feedback winding stops (induction only happens while magnetic field is changing) and voltage from pin 3 to pin 4 starts to drop, decreasing the bias to Q1486.
8. As Q1486 receives less bias, it starts conducting less, decreasing current to T1501's primary.
9. As T1501's primary's current decrease, magnetic field is now decreasing, inducing negative voltage from pin 3 to pin 4 of the feedback winding... this time, subtracting from the bias being provided by R1483, and pushing Q1486 into cutoff... Which further decrease T1501's primary current (and further decreases magnetic field) until the point the Q1486 is completely cutoff, and there's no more current (and no magnetic field) on T1501's primary.
10. When there's no current and no magnetic field anymore on T1501's primary, we're back to step 2, and everything starts over again.
Additionally C1483 plays a role here, interacting with the feedback winding's inductance, to prevent oscillations at overtone frequencies... (I.e. the fundamental frequency is not set by this capacitor, but by the transformer's self resonating frequency, and C1483 helps avoiding the oscillator from running into the harmonics).

In all that, the summed currents from R1483 and additional current coming from Q1484, is what makes Q1486 starts conducting again at the end of each cycle and keeps the oscillation going.
The current from R1483 establishes a baseline (so that the oscillation works minimally), and Q1484 provides the additional current necessary to make the oscillation amplitude to regulate according to a DC feedback loop that comes from the Cathode Voltage (-1470V), and is compared against the +65V (which is the +DC voltage reference for all the supply voltages of the 464) by means of the voltage divider comprised of R1525D (28.36MOhm) and R1525C (1.25MOhm).
This voltage divider, when the Cathode voltage is at the correct value of about -1470V, provides about 0.5 ~ 0.7 V to the base of Q1472 which is just enough to bias it.
If the oscillator starts working too hard, the cathode voltage goes more negative than -1470V, making the voltage at the base of Q1472 to go down, making it conducts less, which makes Q1476 to conduct and so Q1484, which will reduce the drive to the oscillator, which will run with less power and producing less negative voltage to the Cathode (if will go less negative).
The Cathode Voltage DC regulation loop is comprised of: The high value voltage divider (R1525D and R1525C), Q1472, Q1476 and Q1484 (which all their associated biasing resistors).
C1455 and R1455 makes up for a slow start of the H.V. power supply (it makes the reference +65V for the voltage divider to grow slowly).
C1472 and R1472 sets the DC regulation loop time constant, making it not react to fast changes (e.g. ripple and/or noise) and react only to steady changes in Cathode Voltage.
Their values are also set to avoid that the DC regulation loop itself oscillates (which would be apparent as the Cathode voltage to keep constantly going up and down around the -1470V threshold).

KRgrds,

Fabio

On Fri, Aug 24, 2018 at 03:58 AM, Jim Olson wrote:


Fabio I have been following this thread out of curiosity and looking at the
schematic in my 466 book for this circuit and it is weird. If Q1486 does not
have a good ground to mains earth it seems to me it wont work correctly? Why
the two primary windings? for that HV transformer and how is the AC created to
make it function?

Jim

On August 23, 2018 at 10:29 AM Fabio Trevisan <fabio.tr3visan@...>
wrote:


Hello Mark,
OK... so Q1486 is an original Tek (as it has the Tek part number) and it's
checking OK... This is better news than worse... even though it's one less
explanation for the problem, at least it's an original one which is a great
relief, since it being anything else would sure mean bigger problems (to find
one that would work).
As innocent as Q1486 is (being a low frequency transistor), the problem in
this circuit is the circuit itself... From what I learnt on my own 464 issue,
which David Hess was so kind of walking me through, the circuit is so finnicky
that it's more likely for it to not work than it is likely to work.
That said, the "critical" element in it is Q1486 having its parameters just
right (not a matter of being outstanding, nor poor, but just right)... and
that is what you get when you have the correct Q1486 part number (which you
got, bingo!).
Now, while the transistor is the correct one (and seems to be in working
order), it's still true that the circuit is finnicky and works very
marginally, so it doesn't take much for it to not work.
If it would be me, I would start by disconnecting from T1501, everything
that's not strictly necessary for the H.V. regulation feedback loop to
work...Namely:
1. The output to the voltage doubler (the whole voltage doubler board that
is on the side of the 464.
2. The diode that recitfies the +600V that goes to the Storage board (and
keep the NON STORE button pressed).

There's no harm in operating the scope without either of those voltages.
Without the voltage doubler there won't be 7kV of Post Deflection
Acceleration, but as I was once thaught, the CRT would still work (although
very dim and with a wrong deflection factor).

That's for a start... and when I have the schematics at hand, I can think of
something else to try.

Rgrds,

Fabio









On Thu, Aug 23, 2018 at 11:52 AM, <kickingypsy9@...> wrote:


i did check Q1486 first time around, its a rca but it also has 151-0140 on
it
..dont know if its original but it checks ok.i also cleaned the place
where
the wire hooks to it. i took the rca out, and put a 2SC3280 in, and just
soldered it the board to see if it would run.....hooked up my scope to pin
3
and powered it up...wow its running,went to see if i could see any
display,nothing,checked again ,it stoped running.one thing i noticed when
i
powered it off the crt light completly up then faded to a dot in the
center.so
i know the hv came up for a moment.puled out my transister it still checks
ok.i still have Q1492 the protect trans out of circuit.so...i either have
a
intermitted T1501 or somthing weired going on with that oscillator
circuit.i
tried freezing and heating the board,no change. i tend to think its the
circuit,i dont see why that output should be anything speacial.its just a
115wat medium speed audio output.but still changing it made it work for a
second ???what the hecks going on here!!!


Re: 464

Jim Olson <v_12eng@...>
 

Fabio I have been following this thread out of curiosity and looking at the schematic in my 466 book for this circuit and it is weird. If Q1486 does not have a good ground to mains earth it seems to me it wont work correctly? Why the two primary windings? for that HV transformer and how is the AC created to make it function?

Jim

On August 23, 2018 at 10:29 AM Fabio Trevisan <fabio.tr3visan@...> wrote:


Hello Mark,
OK... so Q1486 is an original Tek (as it has the Tek part number) and it's checking OK... This is better news than worse... even though it's one less explanation for the problem, at least it's an original one which is a great relief, since it being anything else would sure mean bigger problems (to find one that would work).
As innocent as Q1486 is (being a low frequency transistor), the problem in this circuit is the circuit itself... From what I learnt on my own 464 issue, which David Hess was so kind of walking me through, the circuit is so finnicky that it's more likely for it to not work than it is likely to work.
That said, the "critical" element in it is Q1486 having its parameters just right (not a matter of being outstanding, nor poor, but just right)... and that is what you get when you have the correct Q1486 part number (which you got, bingo!).
Now, while the transistor is the correct one (and seems to be in working order), it's still true that the circuit is finnicky and works very marginally, so it doesn't take much for it to not work.
If it would be me, I would start by disconnecting from T1501, everything that's not strictly necessary for the H.V. regulation feedback loop to work...Namely:
1. The output to the voltage doubler (the whole voltage doubler board that is on the side of the 464.
2. The diode that recitfies the +600V that goes to the Storage board (and keep the NON STORE button pressed).

There's no harm in operating the scope without either of those voltages. Without the voltage doubler there won't be 7kV of Post Deflection Acceleration, but as I was once thaught, the CRT would still work (although very dim and with a wrong deflection factor).

That's for a start... and when I have the schematics at hand, I can think of something else to try.

Rgrds,

Fabio









On Thu, Aug 23, 2018 at 11:52 AM, <kickingypsy9@...> wrote:


i did check Q1486 first time around, its a rca but it also has 151-0140 on it
..dont know if its original but it checks ok.i also cleaned the place where
the wire hooks to it. i took the rca out, and put a 2SC3280 in, and just
soldered it the board to see if it would run.....hooked up my scope to pin 3
and powered it up...wow its running,went to see if i could see any
display,nothing,checked again ,it stoped running.one thing i noticed when i
powered it off the crt light completly up then faded to a dot in the center.so
i know the hv came up for a moment.puled out my transister it still checks
ok.i still have Q1492 the protect trans out of circuit.so...i either have a
intermitted T1501 or somthing weired going on with that oscillator circuit.i
tried freezing and heating the board,no change. i tend to think its the
circuit,i dont see why that output should be anything speacial.its just a
115wat medium speed audio output.but still changing it made it work for a
second ???what the hecks going on here!!!


Re: scanned: Common Parts Design Catalog #5, Resistors and Capacitors, March 1989

Jim Olson <v_12eng@...>
 

Thanks for posting these scans this catalog is a extremely useful one it has the info needed to tell which capacitors are what.
There are some pages in the capacitor sections 12 and 13 that did not scan or reproduce in my downloaded copy.
Here is some general info for the 464/466 scopes.
The cross section listings are great used them to sort out which caps are used on the A6 and A10 boards for my 466. FWIW there are a mixed bag of types used on them on A6 two wet axial tants, C-1237, C-1737 C-1237 is the one that leaks it appears as it was on the board I am working on and has been replaced on two others with Alum lytics. There is one dry axial tant C-1487, and three axial tubular foil types C-1452, C-1455, C-1246 (sprague 30D) look like tants. On my board C-1452 was up graded to a newer type foil square type part number changed to a 01 from 00 in the cross reference.

On August 23, 2018 at 7:48 AM Kurt Rosenfeld <kurt.harlem@...> wrote:


This scan was made possible by Pete Lancashire.

https://drive.google.com/open?id=1JqkxPKq6bmYP3SZGz4IP_q43za7AQauk




Re: scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

Leon Robinson
 

Kurt,
I'm curious how many of these Catalogs are there?
 Leon Robinson    K5JLR

Political Correctness is a Political Disease.

From: Kurt Rosenfeld <kurt.harlem@...>
To: TekScopes@groups.io
Sent: Thursday, August 23, 2018 4:45 PM
Subject: Re: [TekScopes] scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

Bob,

Black and white pages were scanned at 600 dpi, bitonal, with lossless compression. Color pages were scanned at 300 dpi, in color, with lossy compression. OCR was done using Acrobat.

-Kurt


7000 series white plug-in connector

Jim Ford
 

Hi, everybody.

The formerly dead 7603 saga continues. The white connector where the
Right Vertical plug-in connects snapped apart last night. It's such a
clean break off the left side (looking into the scope) that it seems
like a bit of epoxy could hold it back on there good as new. Any reason
to avoid doing so?

I'd attach a picture, but how do I do so?

Thanks for your help.

Jim

---
This email has been checked for viruses by AVG.
https://www.avg.com


Tektronix Type 3S2 Sampling Unit W/ S-52 Pulse Generator Head & S-1 SamplingHead, FS @ $ 225

 


Re: scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

Kurt Rosenfeld
 

Bob,

Black and white pages were scanned at 600 dpi, bitonal, with lossless compression. Color pages were scanned at 300 dpi, in color, with lossy compression. OCR was done using Acrobat.

-Kurt


Re: scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

bobh@joba.com
 

Kurt, the scans are just incredible. Could you reveal a bit about the process to achieve such great scans?

For anyone not familiar with these books there is cross reference in the back which takes you from a Tek part number to the page the detailed information is located on.

Bob.

-----Original Message-----
From: Kurt Rosenfeld
Sent: Thursday, August 23, 2018 12:49 PM
To: TekScopes@groups.io
Subject: [TekScopes] scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

This scan was made possible by Pete Lancashire.

https://drive.google.com/open?id=1B1iRXUSpeStpn6SGhMnxjkyQPkeMTfNH


scanned: Common Parts Design Catalog #6, Wire, Insulation, and Power Supplies, May 1988

Kurt Rosenfeld
 

This scan was made possible by Pete Lancashire.

https://drive.google.com/open?id=1B1iRXUSpeStpn6SGhMnxjkyQPkeMTfNH


Re: Tek 371a test bed needed??? Or not

Bob Koller <testtech@...>
 

There is a test fixture required; a large affair, with hinged cover, thick umbilical/connector, interlocks, jumper cables. Nearly impossible to find by itself, although you occasionally see a 371x orphaned without it's fixture.
The fixture accepts the 370x series DUT adapters. The older 576 series will fit, but are not recommended, as the different plugs can damage the gold plated jacks.
Google will show the setup.

The 371 is a pulsed only instrument for high power device testing.


Re: scanned: Common Parts Design Catalog #5, Resistors and Capacitors, March 1989

Dave Daniel
 

Kurt and Pete,

Thank you for providing these. They will be very useful.

DaveD

On 8/23/2018 10:48 AM, Kurt Rosenfeld wrote:
This scan was made possible by Pete Lancashire.

https://drive.google.com/open?id=1JqkxPKq6bmYP3SZGz4IP_q43za7AQauk



Re: 464

Fabio Trevisan
 

Hello Mark,
OK... so Q1486 is an original Tek (as it has the Tek part number) and it's checking OK... This is better news than worse... even though it's one less explanation for the problem, at least it's an original one which is a great relief, since it being anything else would sure mean bigger problems (to find one that would work).
As innocent as Q1486 is (being a low frequency transistor), the problem in this circuit is the circuit itself... From what I learnt on my own 464 issue, which David Hess was so kind of walking me through, the circuit is so finnicky that it's more likely for it to not work than it is likely to work.
That said, the "critical" element in it is Q1486 having its parameters just right (not a matter of being outstanding, nor poor, but just right)... and that is what you get when you have the correct Q1486 part number (which you got, bingo!).
Now, while the transistor is the correct one (and seems to be in working order), it's still true that the circuit is finnicky and works very marginally, so it doesn't take much for it to not work.
If it would be me, I would start by disconnecting from T1501, everything that's not strictly necessary for the H.V. regulation feedback loop to work...Namely:
1. The output to the voltage doubler (the whole voltage doubler board that is on the side of the 464.
2. The diode that recitfies the +600V that goes to the Storage board (and keep the NON STORE button pressed).

There's no harm in operating the scope without either of those voltages. Without the voltage doubler there won't be 7kV of Post Deflection Acceleration, but as I was once thaught, the CRT would still work (although very dim and with a wrong deflection factor).

That's for a start... and when I have the schematics at hand, I can think of something else to try.

Rgrds,

Fabio

On Thu, Aug 23, 2018 at 11:52 AM, <kickingypsy9@...> wrote:


i did check Q1486 first time around, its a rca but it also has 151-0140 on it
..dont know if its original but it checks ok.i also cleaned the place where
the wire hooks to it. i took the rca out, and put a 2SC3280 in, and just
soldered it the board to see if it would run.....hooked up my scope to pin 3
and powered it up...wow its running,went to see if i could see any
display,nothing,checked again ,it stoped running.one thing i noticed when i
powered it off the crt light completly up then faded to a dot in the center.so
i know the hv came up for a moment.puled out my transister it still checks
ok.i still have Q1492 the protect trans out of circuit.so...i either have a
intermitted T1501 or somthing weired going on with that oscillator circuit.i
tried freezing and heating the board,no change. i tend to think its the
circuit,i dont see why that output should be anything speacial.its just a
115wat medium speed audio output.but still changing it made it work for a
second ???what the hecks going on here!!!


Re: 454 no trace

Mark Wendt
 

On Thu, Aug 23, 2018, 12:42 <hfran@...> wrote:

454 worked fine, but had a stalled fan, which I replaced by a 12 VDC fan,
which I supplied from +12v unregulated. But then no trace anymore.
1) HV oscillator does not oscillate. Checked Q1414, G1413, Q1423 and Q
1430 by diode check. All appear to be working, except Q1430 might have too
low hfe, where I cannot be sure by diode check.
2) failure to oscillate could also come from too much loading. I fed
-30v via 1 MOhm to TP1469
( -1960V, when working ) and measured 25 microamp to GND, meaning a leak
resistor from possibly only 200k to GND. Could such a leak current be
normal ? C1469 and C1479 ( unsoldered ) are
( low voltage ) multimeter- measured o.k.
Since there could be many caps and diodes defective I would need a
strategy to follow, because to replace Q1430 is complicated and might still
not cure the failure.
Has anybody experienced such a failure or has some idea or strategy.That
would be extremely helpful.
What happens if you temporarily disconnect the fan and power up for a short
period of time?

Maybe the new fan is drawing too much from the circuit?

Mark



454 no trace

hfran@...
 

454 worked fine, but had a stalled fan, which I replaced by a 12 VDC fan, which I supplied from +12v unregulated. But then no trace anymore.
1) HV oscillator does not oscillate. Checked Q1414, G1413, Q1423 and Q 1430 by diode check. All appear to be working, except Q1430 might have too low hfe, where I cannot be sure by diode check.
2) failure to oscillate could also come from too much loading. I fed -30v via 1 MOhm to TP1469
( -1960V, when working ) and measured 25 microamp to GND, meaning a leak resistor from possibly only 200k to GND. Could such a leak current be normal ? C1469 and C1479 ( unsoldered ) are
( low voltage ) multimeter- measured o.k.
Since there could be many caps and diodes defective I would need a strategy to follow, because to replace Q1430 is complicated and might still not cure the failure.
Has anybody experienced such a failure or has some idea or strategy.That would be extremely helpful.


Re: 464

kickingypsy9@...
 

i did check Q1486 first time around, its a rca but it also has 151-0140 on it ..dont know if its original but it checks ok.i also cleaned the place where the wire hooks to it. i took the rca out, and put a 2SC3280 in, and just soldered it the board to see if it would run.....hooked up my scope to pin 3 and powered it up...wow its running,went to see if i could see any display,nothing,checked again ,it stoped running.one thing i noticed when i powered it off the crt light completly up then faded to a dot in the center.so i know the hv came up for a moment.puled out my transister it still checks ok.i still have Q1492 the protect trans out of circuit.so...i either have a intermitted T1501 or somthing weired going on with that oscillator circuit.i tried freezing and heating the board,no change. i tend to think its the circuit,i dont see why that output should be anything speacial.its just a 115wat medium speed audio output.but still changing it made it work for a second ???what the hecks going on here!!!


scanned: Common Parts Design Catalog #5, Resistors and Capacitors, March 1989

Kurt Rosenfeld
 

This scan was made possible by Pete Lancashire.

https://drive.google.com/open?id=1JqkxPKq6bmYP3SZGz4IP_q43za7AQauk